Practical application of aqueous two-phase systems for the development of a prototype process for c-phycocyanin recovery from Spirulina maxima
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A novel process for the recovery of c-phycocyanin from Spirulina maxima exploiting aqueous two-phase systems (ATPS), ultrafiltration and precipitation was developed in order to reduce the number of unit operations and benefit from an increased yield of the protein product. The evaluation of system parameters such as PEG molecular mass, concentration of PEG as well as salt, system pH and volume ratio was carried out to determine under which conditions the c-phycocyanin and contaminants concentrate to opposite phases. PEG1450-phosphate ATPS proved to be suitable for the recovery of c-phycocyanin because the target protein concentrated in the top phase whilst the cell debris concentrated in the bottom phase. A two-stage ATPS process with a phase volume ratio (Vr) equal to 0.3, PEG1450 7% (w/w), phosphate 20% (w/w) and system pH of 6.5 allowed c-phycocyanin recovery with a purity of 2.4 (estimated as the relationship of the 620 nm to 280 nm absorbances). The use of ultrafiltration (with a 30kDa membrane cut-off) and precipitation (with ammonium sulfate) resulted in a recovery process that produced a protein purity of 3.8±0.1 and an overall product yield of 29.5% (w/w). The results reported here demonstrated the practical implementation of ATPS for the design of a prototype recovery process as a first step for the commercial purification of c-phycocyanin produced by Spirulina maxima. © 2001 Society of Chemical Industry.